Downhole hydraulic pumps of the free type employ a sealing means for packing off or separating the high pressure power fluid used to operate a subsurface hydraulic oil well pump. In particular, the seal is useful in conjunction with a free type pump which can be pumped or circulated downhole into seated relationship respective to an o-ring collar, and when it is necessary to retrieve the pump, pressure can be applied at the well head to force the pump back uphole to the surface of the ground.
In order to install a free type pump downhole in a borehole, it is necessary to flow the pump down the tubing string until an o-ring seal located on the pump body is sealingly received in the o-ring collar located at the lower end of the tubing string. This expedient separates the power oil from the produced fluid, and should the o-ring become damaged and leak, the two fluids naturally mix whereupon great loss in efficiency is experienced, dependent upon the magnitude of the leakage.
When the pump is initially forced back uphole, the high pressure fluid located below the o-ring tends to cause the o-ring to flow out from its groove as the o-ring leaves its collar, thereby breaking the o-ring.
The above manipulations often damage the o-ring and eventually causes it to break so that it is free to fall into the bottom of the borehole where it is ingested into the pump, thereby causing malfunction and expensive repairs.
It would therefor be desirable to have made available an o-ring seal assembly for a free type downhole pump which is less liable to malfunction in the above manner, which will not roll upon itself as it becomes seated, and which is not liable to be pumped out of its groove as the pump is unseated. Furthermore, it is desirable to have made available means by which a broken o-ring will be retained within its groove rather than being ingested into the pump intake.